She added: “They looked at every aspect of his life, his personality, his home, everything was scrutinised.”

Neighbours in the quiet cul-de-sac in Hatfield, Herts, where the Wheatleys lived saw paramedics carry Alexa to an ambulance. She died in hospital.

One tearful woman, who asked not to be named, said: “When she was carried out, the girl was attached to wires and her skin was pale white. Her hair was wet and her legs were floppy.”

Another neighbour revealed that Carl quit his job at a local Asda supermarket to look after his girl.

She said the dad spent months decorating the home for his daughter after moving to the area last November and went on: “She was a little angel. She was just an innocent little girl, always happy playing.

“I went round to their house once and she was banging away on some drums.

South Beds News Agency

Happy: Carl and Lexie

“Carl gave up his job to take care of her. He was so looking forward to living with her.

"He did the house up so she could move in. He seemed quite lonely though.”

Another neighbour said: “She was such a pretty little girl. It is a tragedy.”

Alexa attended afternoon classes at nearby Howe Dell School. No one there was available for comment.

Detectives said the dad and his child were the only people in the house.

A police spokesman confirmed that a 30-year-old man from Hatfield had been arrested on suspicion of murder.

The cause of death is not yet known and a postmortem is due on Monday.